Hey ya'll
I'm just checking in as I'm new to the forum. What actually brought me here is I suddenly starting having a whistling howling noise from back of the cab when heat is on. Doesn't matter if I'm moving. Sitting still with heat on defog/floor with fan on low is most noticeable but its stays constant unless I shut off defog and go to recirc. Bought truck brand new in Jan 11 and this is a sudden new nusiance noise. So web search brought me here

Paul
aka stingrayboots